1. Field of the Invention
The present invention generally relates to compressors, and more particularly, to an improved gasket for sealing between compression and suction chambers in a compressor.
2. Description of the Related Art
Typical compressors include a cylinder block having a plurality of cylinder bores defined therein. A piston is accommodated in and reciprocates with respect to each cylinder bore. Front and rear housings are secured to the front and rear end faces of the cylinder block with a valve plate in between, respectively. Each housing includes a bulkhead formed therein. Each housing, the associated valve plate and the cylinder block define suction and discharge chambers. Suction and discharge valve mechanisms are formed on both sides of the valve plate. The suction and discharge mechanisms correspond to the suction and discharge chamber, respectively.
A compressor of the above structure includes, for example, a discharge valve mechanism as illustrated in FIG. 6. A first plate 43 and a gasket 44 are located between a valve plate 41 and a housing 42. A plurality of discharge port 45 (only one is shown) are formed in the valve plate 41, each corresponding to one of the cylinder bores. A plurality of discharge valve flaps 43a are formed on the first plate 43. Each flap 43a corresponds to one of the valve port 45. Each flap 43a selectively opens and closes the corresponding port 45.
The gasket 44 includes an annular seal 44a (see FIGS. 5 and 6) the width of which is substantially the same as that of a bulkhead 42a of the housing 42. The seal 44a is held between the distal end of the bulkhead 42a and the valve plate 41 thereby sealing a suction chamber 46 defined in the housing 42 from a discharge chamber 47 defined in the housing 42.
The gasket 44 also includes retainers 44b integrally formed with the seal 44a. Each retainer 44b defines the opening amount of the corresponding discharge valve flap 43a. When highly pressurized refrigerant gas is discharge to the discharge chamber 47, the gas causes the associated discharge valve flap 43a to flex to an open position, which is defined by the retainer 44b. The force of the refrigerant gas pushes the inner wall of the discharge chamber 47 in a direction away from the valve plate 41. If the contact pressure of the valve plate 41 and the distal end face of the bulkhead 42a with the seal 44a in between is not great enough, the force of the gas partly separates the seal 44a from the valve plate 41. This deteriorates the sealing between the suction chamber 46 and the discharge chamber 47 and causes compressed gas in the discharge chamber 47 to leak into the suction chamber 46. The compression efficiency of the compressor in thus reduced.
Since the retainer 44b and the seal 44a are integrally formed, refrigerant gas discharged to the discharge chamber 47 presses each discharge valve flap 43a against the corresponding retainer 44b with a great force. As shown in FIG. 7, a force f1 acting on the retainer 44b generates an angular moment M0 the center of which is a contact point A0 of the inner edge of the bulkhead 42a and the seal 44a of the gasket 44. A reactive force f0 is generated at the contact point B0 of the valve plate 41 and the outer edge of the seal 44a in accordance with the angular moment M0. A resultant force f1+f0 is generated at the contact point A0. The force f1+f0 pushes the bulkhead 42a away from the valve plate 41.
Since the width of the seal 44a is substantially the same an that of the bulkhead 42a, the center A0 of the angular moment M0 is relatively close to the point of application B0 or the reactive force f0. The shorter the distance between the center A0 of the moment and the reactive force f0, the greater the magnitude of the reactive force f0 becomes. If the reactive force f0 is increased, the force f1+f0, which pushes the housing 42 away from the valve plate 41, is increased, accordingly. Thus the housing 42 becomes more likely to separate from the valve plate 41.